Disgorgement

Disgorgement
Disgorgement is the process that ejects the sediment under the force of the pressure in the bottle. First the bottle must be opened, turning it upright in the process.

This can be done in one of two ways:

à la volée, is the method that requires no preparatory steps. The disgorger holds the bottle vertical or slightly angled against his left forearm, the base level with the crook of his arm. He then applies the key (or disgorgement pincers) to the cap, brings the bottle upright and swiftly pulls off the crown cap (or metal clip). As the bubble of carbon dioxide meets the sediment, both the plastic bidule (or cork) and sediment are driven out by the pressure.

It remains for him to check the clarity of the wine, using his nose to check for the smallest abnormal aroma, then blocking the neck with the thumb of the left hand as he places the bottle on the dosage machine.

A firm hand and considerable experience are essential to maintain an average rate of 400 bottles disgorged per day. If the bottle is turned upwards too soon, the sediment will mix back into the wine and make it unfit to drink. If on the other hand the bottle is not angled correctly, a large quantity of wine will be lost.

à la glace is the method where the deposit is first frozen in the neck of the bottle, by plunging the neck into a refrigerated tank of brine at a constant temperature of around -25oC. This creates a 4cm long ice plug in which the sediment is trapped. After several minutes, the bottle is turned upright and the cap removed. The pressure drives out the stopper plus the ice plug with the deposit trapped inside it.

Modern disgorging units increase the rate of uncapping 20-fold, while also taking the load off the cellar workers.
Something astonishing happens as the bottles are opened: there is no escape of gas – barely a trace of mousse. Low temperature has something to do with it, as does the carbon dioxide supersaturation that occurs in the course of second fermentation. Mainly though, this is thanks to extremely delicate handling, being careful not to knock the sides of the bottle. The slightest bump will cause an explosion of the imprisoned carbon dioxide, sending the contents gushing out like a hydrant.

The rate of disgorgement ranges from 2000 to 18,000 bottles per hour, depending on the level of mechanisation and automation. Modern disgorging facilities normally include:

A system that picks up the bottles by the neck from the riddling (remuage) palette and places them head down in the disgorgement tank,

A freezing tank that produces the ice plug,

A system to turn the bottles back upright on the line as they leave the tank,

A dégorgeuse, which is basically a specialised uncapping machine,

A doseuse to add the dosing liquor (liqueur d’expedition), equipped with: one emptying nozzle (to make space for the liquor); one liquor-dispensing nozzle; one refilling nozzle,

A boucheuse (corking machine),

A museleuse (wire-hooding machine),

A retourneur (bottle-turning machine to ensure the even mixing of wine with the dosing liquor),

A bottle palletizer to repack the bottles in palette crates, ready for labelling.